SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '457a8d0b8ad72eb8ee88cd9106fe895b7b06e809804b70de186d6af862e3b6e4' 
  AND token = 'QVztmQjpYKsTEmUfQgCps4vhYZZPvlCZuQ07ZKlA/z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}